1. Field of the Invention
This invention relates to a compressed air system, such as an air charging system used in trucks or heavy vehicles.
2. Discussion of the Art
Trucks and heavy vehicles use pressurized air systems for braking, suspension, and auxiliary uses. For example, a compressor is driven by the vehicle engine and a governor associated with the compressor selectively loads and unloads the compressor as required for system operation.
Preferably, before the air is conveyed downstream for use or storage in a reservoir, the air is cleaned since a residual amount of oil, oil vapor, water, and water vapor flows through the compressor discharge line. An oil separator and an air dryer are commonly used to clean the air flow. The oil separator preferably removes water in liquid form, as well as oil in vapor and aerosol form, and solid contaminants. The air then exits the oil separator and passes through a desiccant or drying material. The desiccant adsorbs the water vapor to the desiccant material where the moisture is periodically purged from the air dryer. This arrangement removes approximately 95% of the water vapor in the pressurized air.
It is also contemplated that an oil separator can be positioned at other locations downstream of the compressor. Accordingly, this improvement is not limited to those systems where the oil separator is disposed adjacent the compressor or air dryer, but is more generally applicable for use in a compressed air system where needed.
If an undue restriction occurs in the oil filter element, it is still necessary to convey the compressed air downstream. That is, air is still required for downstream uses such as braking, suspension, so that a need exists for automatically bypassing the oil separator under certain conditions.